Process for the selective preparation of Z-isomers of 3-2(substituted vinyl)cephalosporins

ABSTRACT

There can be produced, at a high selectivity and in a high yield, the Z-isomer of a 7-N-unsubstituted or substituted-amino-3-[2-(4-substituted or unsubstituted-thiazol-5-yl) vinyl]-3-cephem-4-carboxylic acid or an ester thereof having the general formula (IV)                    
     wherein R 1  denotes a hydrogen atom, a mono-valent amino-protecting group or a 2-(2-N-protected or unprotected aminothiazol-4-yl)- 2-alkoxyiminoacetyl group, R 2  denotes a hydrogen atom, or R 1  and R 2  as taken together mean one di-valent amino-protecting group, R 3  denotes a hydrogen atom, pivaloyloxymethyl group or a carboxyl-protecting group and R 8  denotes an alkyl group and so on, by a process comprising reacting a 7-N-unsubstituted or substituted-amino-3-[(tri-substituted-phosphoranylidene) methyl]-3-cephem-4-carboxylic acid or an ester thereof having the general formula (I)                    
     wherein R 1 , R 2  and R 3  each have the same meanings as defined above, and R 4  denotes a lower alryl group or an aryl group, with a 4-substituted or unsubstituted-thiazol-5-carbaldehyde in a mixed solvent consisting of a mixture of one or more chlorinated hydrocarbon solvent(s) with one or more lower alkanol(s) at a low temperature of +5° C. or below. According to the processes of this invention, the production of such E-isomer of the compound (IV) that is of lower antibacterial activity than that of the Z-isomer can be suppressed remarkedly. Further, the Z-isomer of a high purity can be produced efficiently in a facile way.

TECHNICAL FIELD

This invention relates to a novel process for producing selectively andin a high yield the Z-isomer (cis-isomer) of a cephalosporin antibiotichaving a 2-(4-substituted or unsubstituted-thiazol-5-yl)vinyl group asthe 3-substituent, or the Z-isomer (cis-isomer) of such a7-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or aprotected derivative thereof which is utilizable as an intermediate forthe synthesis of the said cephalosporin antibiotic. This invention alsorelates to a novel process for producing efficiently and in a facile waya highly pure Z-isomer (cis-isomer)of a7-[2-(2-aminothiazol-4-yl)-2-alkoxyiminoacetamido]-3-[2-(4-substitutedor unsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid, or a7-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or aprotected derivative thereof.

BACKGROUND ART

Japanese Patent Publication No. Hei 3-64503 (Japanese Patent No.1698887), U.S. Pat. No. 4,839,350 or European Patent No. 0175610specification discloses7-[2-methoxyimino-2-(2-amino-thiazol-4-yl)acetamido]-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylicacid (syn-isomer, cis-isomer) represented by the following formula (A)

This compound is an excellent cephalosporin antibiotic called as“Cefditoren”. The excellent antibacterial activity of Cefditoren againstgram-negative bacteria is attributable to the fact that the Cefditorencompound has the Z-configuration such that the cephem ring and the4-methylthiazol-5-yl group of Cefditoren are connected in thecis-configuration to the carbon-carbon double bond of the 3-vinyl groupof the Cefditoren molecule.

7-[2-Methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylicacid pivaloyloxymethyl ester (syn-isomer, cis-isomer), which is derivedby esterifying the 4-cartboxyl group of the above-mentioned Cefditorencompound with pivaloyloxymethyl group, is represented by the followingformula (B)

and is a pro-drug known as a general name “Cefditoren pivoxil” (refer to“Merck Index” 12th Edition, Page 317). In cases of the3-(2-substituted-vinyl)-cephalosporin antibiotics, it is generally knownthat the Z-isomer (cis-isomer) is superior to the E-isomer(trans-isomer) in the various properties of the antibiotics.

The above-mentioned 3-(2-substituted-vinyl)-cephalosporin antibioticsincluding Cefditoren, or intermediates usable for the synthesis of saidantibiotics may be prepared by various processes. As one of theprocesses available for the production of these antibiotics, there isknown a process using Wittig's reaction. Such a process for thepreparation of the 3-(2-substituted-vinyl)-cephalosporin antibiotics orthe intermediates for their synthesis which comprises using Wittig'sreaction is disclosed, for example, in Japanese Patent Application firstpublication KOKAI Hei-3-264590 or the corresponding U.S. Pat. No.5,233,035 or European Patent Application Publication No. 0175610A2; the“Journal of Antibiotics” XLIII, No. 8, pages 1047-1050 (1990), “Chem.Pharm. Bull.” Vol. 39, No. 9, pages 2433-2436(1991), and internationalPublication No. W095/09171 (published on Apr. 6, 1995) of PCTApplication No.PCT/JP94/01618 or the corresponding European PatentApplication Publication No. 0734965A1 specification. By conducting theWittig's reaction step in accordance with the prior art processes, theresultant reaction product has always been given in the form of amixture of the Z-isomer and E-isomer of the produced compound.

For example, the “Journal of Antibiotics” XLIII, No. 8, pages 1047-1050and “Chem. Pharm. Bull.” Vol. 39, No. 9, pages 2433-2436 mentioned abovedisclose a process for the preparation of such 4-methoxybenzyl ester of7-β-phenylacetamido-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylicacid, which may be used for the synthesis of the aforesaid7-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyirnino-acetamido]-3-(Z)-(4-methylthiazol-5-yl)vinyl-3-cephem-4-carboxylicacid. In this process, there are carried out the steps of treatingp-methoxybenzyl ester of7-β-phenylacetamido-3-chloromethyl-3-cephem-4-carboxylic acid withsodium iodide in acetone to produce the corresponding 3-iodomethylderivative; treating this derivative with triphenylphosphine to producethe corresponding triphenylphosphonium iodide derivative; and reactingthis triphenylphosphonium iodide derivative with5-formyl-4-methylthiazol by the Wittig's reaction at room temperature ina heterogeneous reaction medium comprising dichloromethane (i.e.methylene chloride) and water in the presence of sodium hydrogencarbonate, thereby to produce the 4-methoxybenzyl ester of7-β-phenylacetamido-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylicacid.

The above-mentioned process may be expressed by the following reactionscheme:

In the above-mentioned process, there is produced, as an intermediateproduct, 4-methoxybenzyl ester of 7-β-phenylacetamido-3-[(triphenylphosphoranylidene)methyl]-3-cephem-4-carboxylic acid offormula (F) above, which is then reacted with 5-formyl-4-methylthiazoleby the Wittig's reaction to produce 4-methoxybenzyl ester of7-β-phenylacetamido-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylicacid of formula (H). The reaction product of formula (H) is described inthe above-mentioned literature to have been obtained in the form of amixture of the Z-isomer (cis-isomer) and E-isomer (trans-isomer) of thecompound (H) at a mix ratio of 4.7:1.

The above literature “Journal of Antibiotics” describes that the mixedZ-isomer and E-isomer of the compound of formula (H) is difficult to beisolated from each other even by treating with a column chromatographictechnique. Then, said literature further discloses that the Z-isomer ofthe target product could be isolated only by effecting amethodcomprising removing the 7-phenylacetyl group fro:m the compound offormula (H) by a deprotection technique, condensing the 7-position ofthe deprotected product with2-(2-tritylaminothiazol-4-yl)-2-methoxyimino-acetic acid, subjecting theresulting condensation product to a deprotection reaction, thensubjecting the resulting deprotected product to a column chromatographywith a non-ionic porous resin, and further subjecting the resultingproduct so purified to a fractional crystallization. Thus, the yield ofthe desired Z-isomer as finally harvested was necessarily low to aconsiderable extent.

Further, Japanese Patent Application First Publication KOKAIHei-7-188250 or the corresponding U.S. Pat. No. 5,616, 703 or EuropeanPatent Application Publication No. 658558A1 specification discloses thatthe reaction product, which comprised7-amino-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid ora derivative thereof having the following formula (J)

where R is a protecting group of silyl type or a hydrogen atom and whichwas produced by the Witting's reaction, is a mixture of the Z-isomer andE-isomer. The Japanese Patent Application First Publication KOKAIHei-7-188250 specification also discloses a method for the isolation ofthe Z-isomer which comprises converting the Z/E mixture of7-amino-3-[2-(4-methylthiazol-5-yl)vinyl]3-cephem-4-carboxylic acid intoa corresponding amine salt and subjecting the amine salt so obtained toa recrystallization step. This Publication further discloses that whenthe said Z/E mixture is subjected to a chromatography, there can beobtained the Z-isomer from which the E-isomer of a lower activity hasbeen removed as much as possible.

Further, the above-mentioned PCT International Publication No.WO95/09171 discloses a process which comprises the steps of treating aphosphonium halide compound represented by the following formula (K)

where X is CH or N, R¹¹ is an amino group or a protected amino group,R¹² is a hydrogen atom or a hydroxyimino-protecting group, R¹³ is ahydrogen atom, a salt-forming cation or a carboxyl-protecting group, R¹⁶is an aryl group, for example, a phenyl group, and W is a halogen atom,with a base such as sodium hydrogen carbonate in acetone,tetrahydrofuran, methylene chloride or water at room temperature, toproduce a tri-aryl phosphoranylidene compound represented by thefollowing formula (L)

where R¹¹, R¹², R¹³ and R¹⁶ have the same meanings as defined above,then reacting the compound of formula (L) with a 4-substituted orunsubstituted-thiazol-5-carbaldehyde of the following formula (G′)

where R¹⁴ is a hydrogen atom, R¹⁵ is a hydrogen atom, a lower alkylgroup, a halo-lower alkyl group or a halogen atom, by the Wittig'sreaction at room temperature or under cooling in methylene chloride,methylene chloride-water, tetrahydrofuran or dioxane, to produce a3-vinyl-cephem compound represented by the following formula (N)

where R¹¹, R¹², R¹³, R¹⁴ and R¹⁵ have the same meanings as definedabove. In this prior art process, the resultant reaction product whichcomprises the 3-vinyl-cephem compound of formula (N) as obtained byreacting the phosphoranylidene compound of formula (L) with the aldehydecompound of formula (G′) through the Wittig's reaction, was also in theform of a mixture of Z-isomer (cis-isomer) and E-isomer (trans-isomer)of the compound (H). In order to isolate and recover the desiredZ-isomer from the 3-vinyl-cephem compound of formula (N), it wasnecessary for the above-mentioned process that the reaction solution asobtained from the Wittig's reaction step was at first washed with anaqueous sodium chloride solution, then dried over anhydrous magnesiumsulfate and further concentrated under a reducedl pressure and that theresulting concentrate residue was further purified by a chromatographyso as to separate thes Z-isomer from the E-isomer. Thus, in this priorart process, the yield of the desired Z-isomer of the 3-vinyl-cephemcompound of formula (N) was, in fact, not satisfactorily high, too. Withthe prior art processes for the production of the 3-vinyl-cephemcompound which comprise using the Wittig's reaction, there cannot befound any precedent case where a lower alkanol is used in the reactionmedium for the Wittig's reaction.

Therefore, when there has been carried out the process for theproduction of a cephalosporin compound having the 3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl group which comprises reacting such a7-[2-(2-aminothiazol-4-yl)2-alkoxyiminoacetamido]-[3-(tri-substituted-phosphoranylidene)methyl]-3-cephem-4-carboxylicacid or an ester thereof as embraced by thecompound of formula (L) above, or a 7-amino-or 7-N-protectedamino-3-[(tri-substituted-phosphoranylidene)methyl]-3-cephem-4-carboxylic acid or an ester thereof, with a4-substituted or unsubstituted-thiazol-5-carbaldehyde of formula (G′)through the Wittig's reaction, there has been presented a demand forproviding such a novel process for the production of the3-(2-substituted-vinyl)-cephalosporin compounds which would be capableof producing selectively the desired Z-isomer (cis-isomer) of the3-(2-substituted-vinyl)-cephalosporin compounds in a significantlyhigher proportion than that of the undesirable E-isomer (trans-isomer)of the 3-(2-substituted-vinyl)-cephalosporin compounds.

It has also been presented a demand for providing such a novel processfor the production of the 3-(2-substituted-vinyl)-cephalosporins whichwould be capable of recovering the desired Z-isomer of the finalcephalosporin product in a high yield and at a high purity directly fromthe resulting reaction solution of the Wittig's reaction, withoutinvolving any necessity to carry out any further specific purificationstep for separating the desired Z-isomer from the E-isomer as formed.

DISCLOSURE OF INVENTION

Thus, the prior art processes fcr the production of the3-(2-substituted-vinyl)-cephalosporin, which comprises using theWittig's reaction, have such various drawbacks that the selectivity ofthe production of the Z-isomer is poorer as compared with that of theE-isome, that the isolation of the Z-isomer from the E-isomer hasrequired some additional and complicated operations, and that the actualyield of the Z-isomer is unsatisfactorily low.

Further, in practising the above-mentioned prior art processes, therewas employed the conventional procedure such that the step of theWittig's reaction was carried out with using, in substantially allcases, methylene chloride or methylene chloride-water as the reactionmedium, and with using the room temperatures for the reactiontemperature.

We, the present inventors, have carried out our extensive investigationswith the intention of providing such a novel process for the productionof the 3-(2-substituted-vinyl)-cephalosporins which is free from thedrawbacks of the prior art processes as mentioned above. In particular,we have concentrically studied on the reaction medium, reactiontemperature and other reaction conditions which are available forWittig's reaction. As a result, we now have surprisingly found that, ifa mixed solvent consisting of a mixture of a chlorinated hydrocarbonsolvent with a lower alkanol as mixed at a certain mix ratio (by volume)is used as the reaction medium for the Wittig's reaction, and if,simultaneously, a temperature of 5° C. or below, preferably of 0°C.˜−50° C. is used as the reaction temperature for the Wittig'sreaction, it is feasible to produce the desired Z-isomer of the3-(2-substituted-vinyl)-cephalosporin, in a significantly higher largerproportion than that of the undesirable E-isomer in the reactionsolution of the Witting's reaction, so that the selectivity of theproduction of the desired Z-isomer is thus improved and the yield of theZ-isomer is enhanced. On the basis of these our findings, we havecompleted this invention.

According to a first aspect of this invention, therefore, there isprovided a process for the selective production of the Z-isomer of a7-N-unsubstituted or substituted-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or an esterthereof represented by the following general formula (IV)

wherein R¹ denotes a hydrogen atom or a mono-valent amino-protectinggroup, or R¹ denotes a 2-(2-N-protected or unprotected-aminothiazol-4-yl)-2-alkoxyiminoacetyl group having the following formula (II)

where R⁵ is a hydrogen atom or a mono-valent amino-protecting group andR⁶ is a hydrogen atom, or R⁵ and R⁶ as taken together mean a di-valentamino-protecting group and R⁷is an alkyl group of 1˜4 carbon atoms andwherein R² denotes a hydrogen atom, or R¹ and R²as taken together mean adi-valent amino-protecting group and R³ denotes a hydrogen atom,pivaloyloxymethyl group or an ester-forming group as acarboxyl-protecting group, and R⁸ denotes a hydrogen atom, an alkylgroup of 1˜4 carbon atoms, trifluoromethyl group or a chloro group,characterized in that said process comprises reacting a7-N-unsubstituted orsubstituted-amino-3-[(tri-substitutesd-phosphoranylidene)methyl]-3-cephem-4-carboxylic acid or an ester thereof represented bythe following generaL formula (I)

where R¹, R² and R³ each have the selme meanings as defined above and R⁴denotes an alkyl group of 1˜6 carbon atoms or an aryl group, or acompound represented by the following general formula (I′)

where R¹ R², R³and R⁴ each have the same meanings as defined above, witha 4-substituted or unsubstituted-thiazol-5-carbaldehyde represented bythe following formula (III)

where R⁸ has the same meaning as defined above, in a mixed solventconsisting of one or more chlorinated hydrocarbon solvent(s) and one ormore lower alkariol(s) as mixed together at a mix ratio (by volume) in arange of from 1:3 to 1:0.25, at a temperature of +5° C. to −50° C.

The process according to the first aspect of this invention is differentfrom the aforesaid prior art processes for the production of the3-(2-substituted-vinyl)-cephalosporins with using the Wittig's reactionin that the process of this invention employs as the reaction mediumsuch a mixed solvent made of a mixture of the chlorinated hydrocarbonsolvent(s) with the lower alkanol(s) as mixed together at a certainspecific mixing ratio, and that the process of this invention employs asthe reaction temperature a temperature of 5° C. or lower. However, theprocess of this invention has no significant differences in respect ofthe other reaction procedures and reaction conditions from those of theprior art processes. In spite of such small differences over the priorart processes, the process of this invention can achieve the productionof the desired Z-isomer of the cephem compounds of formula (IV) in ahigher selectivity and at a higher yield than the E-isomer. This isquite unexpectable.

The compound of general formula (I) which is used as the startingmaterial in the process of the first aspect of this invention may beprepared by a method comprising the steps of (i) treating a3-halomethyl-3-cephem compound of the followimg general formula (V)

where R¹, R² and R³ each have the same meanings as defined above and Wis a chlorine atom or a bromine atom, with sodium iodide or potassiumiodide in a reaction medium, for example, acetone or a mixed solventmade of a mixture of methylene chloride or chloroform with water at roomtemperature, to produce a 3-iodomethyl-3-cephem compound of thefollowing general formula (VI)

where R¹, R² and R³ each have the same meanings as defined above; (ii)reacting the compound o: formula (VI) with a tri-alkylphosphine or atri-arylpho.,phine of the following formula (VII)

P(R⁴)₃  (VII)

Where R4 is an alkyl group of 1˜6 carbon atoms, preferably a straightchain alkyl group, or an aryl group, preferably phenyl group or a(C₁˜C₄)alkyl-substituted phenyl group, in a reaction medium of thenature same as that used in the step (i) above at room temperature, toproduce a tri-alkyl (or aryl)phosphonium-methyl compound of thefollowing general formula (VIII)

where R¹, R², R³ and R⁴ each have the same meanings as defined above;and (iii) reacting the phosphonium-methyl compound of formula (VIII)with an aqueous solution of a base such as sodium hydrogen carbonate orsodium hydroxide in a reaction medium made of, for example, methylenechloride or chloroform-water at room temperature or under ice-cooling toproduce the tri-alkyl (or aryl) phosphoranylidene compound of thegeneral formula (I) shown above. As the starting compound, a compound ofgeneral formula (I′) may be used instead of the compound of generalformula (I) above. It is convenient that the reaction solution which wasobtained in the step (iii) above and containing the compound of generalformula (I) is used as such directly in the process of this invention,so that the process of this invention may continue as “one pot” process,without separation of the compound of general formula (I) from thereaction solution of the said step (iii) of preparing the compound (I).

In the compound of general formula (I) or (I′) used as the startingcompound, the mono-valent amino-protecting group, which may berepresented by R¹ and(or) R⁵, has no particular limitation, so far as itis such an amino-protecting group as conventionally used in thesynthesis of penicillin and cephalosporin compounds.

As examples of such mono-valent amino-protecting groups, there may belisted a substituted or unsubstituted mono(or di or tri)-phenylalkylgroup, for example, benzyl group, benzhydryl group, trityl group; analkanoyl group, for example, formyl group, acetyl group; a lowerallcoxycarbonyl group, for example, methoxycarbonyl group; an aromaticacyl group, for example, benzoyl group, tolyl group; heterocycliccarbonyl group, for example, thiazolylcarbonyl group, tetrazolylcarbonylgroup; an alkanoyl group substituted with an aryl or aryloxy group, forexample, phenylacetyl group, phenoxyacetyl group; an aralkyloxycarbonylgroup, for example, benzyloxycarbonyl group; or an alkanoyl groupsubstituted by a heterocyclic group, for example, imidazolylacetylgroup, thiazolylacetyl group; and the like. Phenylacetyl group isparticularly preferred as the amino-protecting group. In cases where R¹and R², or R⁵ and R⁶ as taken together mean one di-valentamino-protecting group, examples of such di-valent amino-protectinggroup are a substitutedorunsubstitutedaralkylidene group, for example,benzylidene group, salicylidene group and etrahydro-pyranylidene group.

Further, in such compounds of general formula (I) or (I′) where R³represents an ester-forming group as the carboxyl-protecting group, suchester-forming group has no particular limitation, so far as it is such acarboxyl-protecting group available at the 3-position or the 4-positionof penicillins and cephalosporins in their synthesis. As suchester-forming groups for R³, there are exemplified a lower alkyl group,for example, methyl group, ethyl group, t-butyl group; a lower alkenylgroup, for example, vinyl group, allyl group; a lower alkoxyalkyl group,for example, methoxymethyl group, ethoxymethyl group; aloweralkylthioalkyl group, forexample, methylthiomethyl group,ethylthiomelhyl group; a lower alkanoyloxyalkyl group, for example.acetoxymethyl group, butylyloxymethyl group; substituted orunsubstituted mono(or di or tri)-phenylalkyl group, for example, benzylgroup, 4-methoxybenzyl group, benzhydryl group, trityl group, and thelike. 4-Methoxybenzyl group is particularly preferred as saidcarboxyl-protecting group.

Further, R⁴ represents a lower alkyl group or an aryl group. The loweralkyl group for R⁴may be an alkyl group of 1˜6 carbon atoms,particularly methyl group, ethyl group, propyl group, n- or t- butylgroup. Particularly preferred is n-butyl group. As an aryl group for R⁴, phenyl group is particularly preferred.

Examples of the chlorinated hydrocarbon solvents, which constitute themixed solvent to be used as the reaction medium in the process accordingto the first aspect of this invention, include monochloro-, dichloro- ortrichloro-(C₁˜C₂)alkane, preferably methylene chloride (namely,dichloromethane) or chloroform, or dichloroethane, or a mixture of twoor more of them.

The other component of the mixed solvent to be used in the process ofthis invention is a lower alkanol. The lower alkanol may include analkanol of 1˜6 carbon atoms, preferably methanol, ethanol, n-propanol,isopropanol, n-butanol or t-butanol, or a mixture of two or more ofthem. Particularly preferred mixed solvent to be used is a mixtureconsisting essentially of chloroform and n-propanol.

In the process according to this invention, there is used as thereaction medium a mixed solvent made of a mixture of the chlorinatedhydrocarbon solvent(s) with the alkanol solvent(s) as mixed together ata mix ratio (by volume) in a range of 1:3˜1:0.25. Such a mixed solventmade of the mixture of the chlorinated hydrocarbon with the alkanolhaving the mix ratio preferably in a range of 1:1˜1:0.28, morepreferably 1:0.5˜1:0.4 is desirably used. When the mix ratio of thechlorinated hydrocarbon to the alkanol present in the mixed solvent asemployed is outside of the range of 1:3˜1:0.25, the amount of theE-isomer as produced increases, while the amount of the Z-isomer asproduced decreases. The reaction temperature used also influenceslargely on the amount of the Z-isomer as produced. In the process ofthis invention, the reaction is carried out at a reaction temperature inthe range of +5° C.˜−50° C., particularly of 0° C.˜−50° C. Particularly,when the reaction is carried out at a temperature in the range of −10°C.˜−30° C., the amount of the E-isomer as produced remarkably decreases,so that the amount of the Z-isomer as produced can be very much greatlyimproved as compared with that of the E-isomer.

Good results are given if the process according to the first aspect ofthis invention is practised in such a manner that the mix ratio (byvolume) of the chlorinated hydrocarbon solvent and the lower alkanol inthe mixed solvent as used is set in the range of 1:1˜1:0.28, morepreferably in the range of 1:0.5˜−1:0.4, andalso that the reaction of acompound of formula (I) (or I′) with a compound of formula (III) iseffected at a temperature in the range of −10° C.˜−30° C., preferably−18° C.˜−23° C. Further, there is obtained such result that the amountof the Z-isomer produced is outstandingly improved as compared with thatof the E-isomer, when the process according to the first aspect of thisinvention is carried out to conduct the reaction in a mixed solventconsisting of chloroform or dichloromethane and n-propanol as mixed at amix ratio (by volume) in the range of 1:0.25˜1:0.4, at a temperature inthe range of −18° C.˜−23° C.

The process according to the first aspect of this invention mayconveniently be practised by dissolving the compound of formula (I) or(I′) in the mixed solvent as used; cooling the resulting solution to areaction temperature required; adding to the cooled solution acarbaldehyde of formula (III) in an amount stoichiometrically requiredor in excess or in large excess; stirring the resulting reaction mixturewhile maintaining the reaction mixture at the required low reactiontemperature to effect the reaction for 12 ˜20 hours.

After the completion of the reaction, the resulting reaction solution iswashed with an aqueous potassium pyro-sulfite solution added, at need,to eliminate the residual aldehyde compound. Further, if thecarbaldehyde compound of formula (III) has incidentally been reactedwith the amino group of the compound of formula (I) to form a Schiffbase, it is preferred to add an ethanol solution of Girard reagent tothe reaction solution in order to decompose the Schiff base.

The reaction solution, which has been pre-treated as above, is thenwashed with an aqueous sodium chloride solution and then concentrated byevaporating the solvent under a reduced pressure or atmosphericpressure. To the resulting concentrated solution or solid residue isadded methanol, ethyl acetate or butyl acetate, and the resultantmixture is allowed to stand for a certain time to deposit the desiredZ-isomer by crystallization. At this time, the presence of a smallamount or a very small amount of the E-isomer by-produced has no badinfluence on the crystallization of the Z-isomer. Thus, the crystals ofthe Z-isomer so obtained are of a high purity. Therefore, no furtherpurification step(s) such as recrystallization and chromatography isrequired to remove the E-isomer.

Further, we have carried out, as one example of the process according tothe first aspect of this invention, such experiment in which7-phenylacetamido-3-[(triphenyl-phosphoranyl-idene)methyl]-3-cephem-4-carboxylicacid 4-methoxybenzyl ester as one example of the compound of formula (I)was dissolved in a mixed solvent consisting of a mixture of methylenechloride and n-propanol at the mix ratio (by volume) of 1:0.4, followedby adding to the resultant solution 4-methylthiazol-5-yl-5-carbaldehyde,and reacting the resulting reaction mixture at a reaction temperature of−20° C.±2° C. for 14 hours under stirring (see Example 3 hereinaftergiven). After the completion of the reaction, the resulting reactionsolution was subjected to a high performance liquid chromatography(HPLC) to determine the quantitative ratio of the Z-isomer to E-isomerof7-phenylacetamido-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylicacid 4-methoxybenzyl ester as produced in the reaction solution. Theconditions for the determination by HPLC are as follows:

Column: YMC A-312; Diameter 6.0 mm×Height 150 mm

Mobile phase: 0.05M phosphate buffer solution-acetonitrile (1:1)

Wave length of detecting light: 274 nm

It was found that the value of the ratio (Z:E) of the area (Z) under theabsorption peak of the Z-isomer to the area (E) under the absorptionpeak of the E-isomer measured in the chromatogram so obtained was45.4:1. An authentic sample of each of the Z-isomer and E-isomer wasprepared by another route and HPLC data of these samples were preparedfurther. Taking the HPLC data so prepared into consideration, the valueof the ratio (Z:E) of 45.1:1 for the rc.tio of the area (Z) to the area(E) defined above was assessed, revealing that the weight ratio of theZ-isomer to E-isomer present in the aforesaid reaction solution obtainedin the above experiment was 94.6:5.4.

By way of comparison, the experiment just above was repeated except thatthe reaction temperature was set in the range of +25° C.±2° C. in placeof the reaction temperature in the range of −20° C.±2° C. The resultingreaction solution obtained here was determined by HPLC in the samemanner as above. Upon calculation from the numerical data of the arearatio (Z:E) of the area (Z) under the absorption peak of Z-isomer to thearea (E) under the absorption peak of E-isomer measured in thechromatogram so obtained in the comparative experiment, it was foundthat the amount of the E-isomer present in the reaction solution asobtained in the comparative experiment was considerably larger incomparison with the amount of the Z-isomer present therein.

Although the experiments given above are merely an illustration, theabove test results of these experiments may support that the Z-isomercan be remarkably produced preferentially to the E-isomer in accordancewith the process of this first aspect invention.

Incidentally, when the 3-vinyl-3-cephem compound of general formula (IV)as produced by the process according to the first aspect of thisinvention has the residual amino-protecting group or/and the residualcarboxyl-protecting group, such protecting group may be removed by aconventional means. Then, when the deprotected product desired has beenrecovered in a usual way out of the reaction solution coming from theabove-mentioned deprotecticn reaction, it is still possible that theZ-isomer in the form of the deprotected product can be obtained at ahigh purity.

We, the inventors of this invention, have prosecuted our investigationsfurther. As a result, we have found, that when the process according tothe first a.spect of this invention is carried out with choosingmethylene chloride or chloroform as the chlorinated hydrocarbon solventto be used in the mixed solvent and with choosing n-propanol as thelower alkanol, and also when the reaction between the compound offormula (I) and the compound of formula (III) is effected in suchparticular mixed solvent of the mixture of the above two solvents mixedat the mix ratio (by volume) in the range of 1:1˜1:0.28, and is effectedparticularly at a temperature in the range of −10° C.˜−30° C., theamount of the Z-isomer of the product of formula (IV) as produced in theresulting reaction solution is considerably increased much than that ofthe E-isomer. Further, we have found that when the reaction solution soobtained is subjected to the under-mentioned post-treatments to recoverthe Z-isomer therefrom, crystals of the Z-isomer as harvested can beobtained at a high purity and in a high yield.

According to a second aspect of this invention, therefore, there isprovided a process for the production of a highly pure Z-isomer of a7-N-unsubstituted or substituted-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or an esterthereof having the formula (IV) above, which process comprises reactinga 7-N-unsubstituted or substituted-amino-3-[(tri-substitutedphosphoranylidene) methyl]-3-cephem-4-carboxylic acid or an esterthereof having the following general formula (I)

wherein R¹ denotes a hydrogen atom or a mono-valent amino-protectinggroup, or R¹ denotes a 2-(2-N-protected orunprotected-aminothiazol-4-yl)-2-alkoxyiminoacetyl group of thefollowing formula (II)

where R⁵ is a hydrogen atom or a mono-valent amino-protecting group andR⁶ is a hydrogen atom, or R⁵ and R⁶ as taken together mean one di-valentamino-protecting group, and R⁷ is an alkyl group of 1˜4 carbon atoms,and wherein R² denotes a hydrogen atom, or R¹ and R2 as taken togethermean one di-valent amino-protecting group and R³ denotes a hydrogen atompivaloyloxymethyl group or an ester-forming group as acarboxyl-protecting group and R⁴ denotes an alkyl group of 1˜6 carbonatoms or an aryl group, or a compound represented by the followinggeneral formula (I′)

where R¹, R², R³ and R⁴ have the same meanings as defined above, with a4-substituted or unsubstituted-thiazol-5-carbaldehyde represented by thefollowing formula (III)

where R⁸ denotes a hydrogen atom, an alkyl group of 1˜4 carbon atoms,trifluoromethyl group or chlcoro group, in a mixed solvent consisting ofa mixture of methylene chloride, chloroform or dichloroethane withn-propanol as mixed at a mix ratio (by volume) in a range of from 1:1 to1:0.28, at a temperature in the range of −10° C. to −30° C., thereby toobtain the reaction solution containing the Z-isomer of the7-N-unsubstituted or substituted-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or an esterthereof having formula (IV)

where R¹, R², R³and R8 have the same meanings as defined above, thenwashing said reaction solution with an aqueous potassium pyrosulfitesolution, thereafter concentrating the reaction solution, adding to theresulting concentrated solution methanol or butyl acetate or a mixturethereof so as to crystallize the Z-isomer of the compound of formula(IV) out of the solution.

In the process according to the second aspect of this invention, thereaction between the starting compound of formula (I) or (I′) and thecarbaldehiyde compound of formula (III) can be carried out in quite thesame manner as that for the corresponding reaction in the processaccording to the first aspect of this invention. Further, in the processaccording to the second aspect of this invention, the crystals of theZ-isomer can be obtained by the step of crystallizing the Z-isomer frommethanol or butyl acetate added to the said concentrated solution, andthe crystals of the Z-isomer so obtained are containing only a verysmall amount of the E-isomer. Thus, the Z-isomer so obtained is in theform of highly pure crystals of the Z-isomer, and in most cases, itrequires no further purification.

As is clear from the above, this invention is particularly useful forthe preparation of 3- (2-substituted-vinyl)-cephlosporin antibiotics andalso for the preparation of intermediates to be used For the synthesisof said cephalosporin antibiotics.

Best Mode for Carrying Out the Invention

The following Examples illustrate more concretely this invention, butnot limit this invention thereto.

By the way, in the Examples given below, either the reaction solutioncontaining the Z-isomer and E-isomer of the compound of formula (IV) asformed, or the other solutions were subjected to HPLC in order to assessthe ratio between these Z- and E-isomers. The conditions used for theHPLC determination are the same as those used for the HPLC determinationdescribed hereinbefore, which are as follows:

Column: YMC A-312; Diameter 6.0 mm×Height 150 mm

Mobile phase: 0.05M phosphate buffer solution-acetonitrile (1:1 byvolume)

Wave length of detecting light: 274 nm

EXAMPLE 1

(a) In a heterogeneous reaction medium consisting of chloroform(30 ml)andwater (30 ml), were dissolved 4-methoxy-benzyl7-(4-acetylaminobenzylideneimino)-3-chloromethyl-3-cephem-4-carboxylate(5 g), triphenylphosphine (2.7 g) and sodium iodide (1.5 g).

The resulting reaction mixture was subjected to a reaction understirring at a temperature of 32±1° C. for 2.5 hours. The chloroformlayer containing 4-methoxybenzyl7-(4-acetylaminobenzylideneimino)-3-triphenylphosphonium-methyl-3-cephem-4-carboxyldteiodide thus formed was then separated from the resulting reactionsolution.

The chloroform layer so separated was cooled to 3±1° C., and then a coldaqueous NaOH solution (containing 0.51 g of NaOH dissolved in 30 ml ofwater) was added thereto. The resultant mixture was subjected to areaction at about 3° C. for 30 minutes.

(b) The chloroform layer containing 4-methoxy-benzyl7-(4-acetylaminobenzylideneimino)-3-[(triphenyl-phosphoranylidene)methyl]-3-cephem-4-carboxylate so formed was separated from theresulting reaction solution and then dried over magnesium sulfate.

The liquid volume of the chloroform in the chloroform layer so dried wasadjusted to 54 ml by adding an appropriate amount of chloroform to thedried chloroform layer. The resulting chloroform solution of said3-(triphenyl-phosphoranylidene)methyl-cephem compound so formed wascooled to −25° C.±2° C., to which 21.5 ml of n-propanol was then added.The mix ratio (by volume) of chloroform to n-propanol present in theresulting solution was 1:0.4.

To the said solution was added 4-methylthiazol-5-carbaldehyde (9.3 g),and the resulting reaction mixture was subjected to a reaction understirring for 14 hours, while cooling it to −20° C.±2° C.

The resulting reaction solution was washed with an aqueous potassiumpyrosulfite solution and an aqueous sodium chloride solution underice-cooling and was then concentrated. The resulting concentratedsolution was added with methanol to effect crystallization of the targetproduct, so that there were harvested crystals (2.51 g; yield 43.8 %) of4-methoxybenzyl7-(4-acetyl-aminobenzylideneimino)-3-[2-(4-methyl-thiazol-5-yl)vinyl]-3-cephem-4-carboxylate.The crystals were dissolved in methylenia chloride-acetonitrile, and theresulting solution was analyzed by HPLC under the same conditions asmentioned above. It was thus observed that the ratio of the area underthe absorption peak of Z-isomer to the area under the absorption peak ofE-isomer was 32.3:1. As evaluated from this numerical value of the arearatio (Z:E), it is shown that the amount of the E-isomer is very smallin comparison with that of the Z-isomer.

¹H-NMR data of the above compound as harvested in this

EXAMPLE ARE SHOWN BELOW.

¹H-NMR: δ(CDCl₃)

2.18(3H, d, J=7.0 Hz)

2.41(3H,s)

2.24(1H, d, J=18.3 Hz)

3.49(1H, d, J=18.3 Hz)

3.78(3H,s)

5.10(1H, d, J=12.1 Hz)

5.15(1H, d, J=12.1 Hz)

5.23(1H, d, J=5.1 Hz)

5.41(1H, d, J=5.1 Hz)

6.30(1H, d, J=11.7 Hz)

6.54(1H, d, J=11.7 Hz)

6.79-7.82(8H, m)

8.58(1H,s)

8.78(1H,s)

EXAMPLE 2

(a) As the starting compound was used 4-methoxybenzyl7-[(Z)-2-(2-tritylaminothiazol-4-yl)-2-methoxyiminoacetamido]-3-chloromethyl-3-cephem-4-carboxylate(2.6 g). This compound was reacted with triphenylphosphine and sodiumiodide in the same manner as in Example 1(a). The resulting reactionproduct was treated with a cold aqueous NaOH solution in the same way asin Example 1(a).

(b) There was thus obtained a chloroform layer containing4-methoxybenzyl7-[(Z)-2-(2-trityleiminothiazol-4-yl)-2-methoxy-iminoacetamido]-3-[(triphenylphosphoranylidene)methyl]-3-cephem-4-carboxylate. Then, this3-(triphenyl-phosphoranylidene)methyl-3-cephem compound was reacted with4-methylthiazol-5-carbaldehyde in a mixed solvent made of a mixture ofchloroform with n-propanoL (1:0.4)at a temperature in the range of −20°C.±2° C. for 14 hours in the same manner as in Example 1(b).

Thus, there were harvested crystals (2.30 g; yield:80.8%) of4-methoxybenzyl7-[(Z)-2-(2-tritylaminothiazol-4-yl)-2-methoxyiminoacetamido]-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylate.The resulting product was subjectedtoHPLCunder the same conditions asabove-mentioned. The result of the HPLC analysis showed that the ratioof the area under the absorption peak of the Z-isomer to the area underthe absorption peak of the E-isomer in the chromatogram obtained for theabove product was 21.3:1.

¹H-NMR: δ(CDC13)

2.42(3H,s)

2.24(1H, d, J=18.7 Hz)

3.48(1H, d, J=18.7 Hz)

3.80(3H,s)

4.07(3H,s)

5.09(1H, d, J=12.0 Hz)

5.13(1H, d, J=12.0 Hz)

5.98(1H, m)

6.29(1H, d, J=11.7 Hz)

6.59(1H, d, J=11.7 Hz)

6.81-7.71(19H,m)

8.58(1H,s)

EXAMPLE 3

As the starting material was used 4-methoxybenzyl7-phenylacetamido-3-chloromethyl-3-cephem-4-carboxylate (10.5 g). Thereaction of this cephem compound with the reagents and thepost-treatments of thre reaction products were carried out in the samemanner as in Example 1(a) and (b). There were thus harvested crystals(10.2 g; yield: 90.9 %) of 4-methoxybenzyl7-phenylacetamidto-3-[2-(4-methyl-thiazol-5-yl)vinyl]-3-cephem-4-carboxylate.

This product so harvested was analyzed by subjecting it to HPLC underthe same measuring conditions as in those above-mentioned. As a result,it was found that the ratio of the area under the absorption peak of theZ-isomer to the area under the absorption peak of the E-isomer in thechromatogram obtained for said product was 45.4:1. From this numericalvalue, the weight ratio of the Z-isomer to theE-isomer present in saidproduct was calculated to be 17.4:1, of which ratio correspond to94.6:5.4 by numerical conversion. It can be seen from this that theproportion of the E-isomer in the harvested product is extremely smallas compared with that of the Z-isomer.

¹H-NMR: δ(CDC₁₃)

2.40(3H,s)

3.21(1H, d, J=18 Hz)

3.46(1H, d, J=18 Hz)

3.67(2H, d J=3.5 Hz)

3.81(3H,s)

5.06(1H, d, J=5 Hz)

5.07(1H, d, J=5 Hz)

5.15(1H, d, J=12 Hz)

5.88(1H, dd, J=5 Hz and 9 Hz)

6.30(1H, d, J=12 Hz)

6.56(1H, d, J=12 Hz)

6.8-7.4(9H,m)

8.60(1H,s)

EXAMPLE 4

As the starting material was used t-butyl7-phenylacetamido-3-bromomethyl-3-cephem-4-carboxylate (2.8 g). Thereaction of this cephem compound with the reagents and thepost-treatments of the reaction products were carried out in the samemanner as in Example 1(a) and (b). Thus, there were harvested crystals(0.54 g; yield: 54.3%) of t-butyl7-phenylacetamido-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylate.

This product so harvested was analyzed by subjecting it to HPLC underthe same measuring conditions as in those abovementioned. As a result,it was found that the ratio of the area under the absorption peak of theZ-isomer to the area under the absorption peak of the E-isomer in thechromatogram obtained for said product was 29.4:1. From this numericalvalue, the weight ratio of the Z-isomer to the E-isomer present in saidproduct was calculated to be 11.5:1, of which ratio correspond to 92:8by numerical conversion. It can be seen from this that the proportion ofthe E-isomer in the harvested product is extremely small as comparedwith that of the Z-isomer.

¹H-NMR: δ(CDCl₃)

1.35(9H,s)

2.44(3H,s)

3.18(1H, d, J=18.3 Hz)

3.44(1H, d, J=18.3 Hz)

3.65(2H, d, J=2.6 Hz)

5.05(1H, d, J=4.8 Hz)

5.87(1H, m)

6.29(1H, d, J=11.7 Hz)

6.61(1H, d, J=11.7 Hz)

7.26˜7.71(5H, m)

8.61(1H,s)

EXAMPLE 5

(a) 4-methoxybenzyl 7-amino-3-chloromethyl-3-cephem-4-carboxylate (1.1g), triphenylphosphine (0.55 g) and sodium iodide (0.32 g) weredissolved in a heterogeneous reaction medium consisting of chloroform(6.5 ml) and water (6.5 ml). The resulting reaction mixture wassubjected to the reaction at a temperature of 32° C.±1° C. for 2 hours.The chloroform layer containing the resulting reaction product desiredwas separatedfromthereactionsolutionasformed. Aftercooling thechloroform layer so separated to 3±10° C., a cold aqueous NaOH solution(containing 0.17 g of NaOH dissolved in 8.6 ml of water) was added tothe cooled chloroform layer, with which the further reaction wasconducted at a temperature of 3±1° C. for 1 hour and 15 minutes.

(b) A chloroform layer containing 4-methoxybenzyl7-amino-3-[(triphenylphosphoranylidene)methyl]-3-cephem-4-carboxylate soproduced was separated form the resulting reaction solution. Thechloroform layer so separated was dried over magnesium sulfate, andther. an amount of chloroform was added thereto to adjust the liquidvolume of chloroform present in said chloroform layer to 12 ml. Theresulting solution was cooled to 25° C.±2° C., to which was then added4.6 ml of n-propanol, followed by further addition of 1.9 g of4-methylthiazol-5-carbaldehyde. The mix ratio of chloroform ton-propanol in the resulting reaction mixture was 1:0.38 (by volume). Thereaction mixture was cooled to −20° C.±2° C. and subjected to thereaction at −20° C.±2° C. under stirring.

After the completion of the reaction, the reaction solution as obtainedwas washed with an aqueous potassium pyrosulfite solution underice-cooling and was then reacted with Girard reagent Tat 22° C. for 1hour after adding an ethanol solution (6.7 ml) of Girard reagent T (0.67g). The resulting reaction solution was washed with an aqueous sodiumchloride solution and then concentrated. Crystallization of the reactionproduct was effected by adding butyl acetate to the resultingconcentrated solution. Thus, there were harvested crystals (0.50 g;yield: 56.0%) of 4-methoxybenzyl7-amino-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylate.

This product so harvested was analyzed by subjecting it to HPLC underthe same measuring conditions as those mentioned above. As a result, itwas found that the ratio of the area under the absorption peak of theZ-isomer to the area under the absorption peak of the E-isomer in thechromatogram obtained for the harvested product was 31.9:1. From thisnumerical value, the weight ratio of the Z-isomer to the E-isomerpresent in said product was calculated to be 13.3:1, of which ratiocorrespond to 93:7 by numerical conversion. It can be seen from thisthat the proportion of the E-isomer in the harvested product isextremely small as compared with that of the Z-isomer.

¹H-NMR: δ(DMSO-d₆)

2.43(3H,s)

2.54(2H,s)

3.79(3H,s)

5.15(2H, d, J=4.3 Hz)

5.22(1H, d, J=5.1 Hz)

5.32(1H, d, J=5.1 Hz)

6.58(1H, d, J=12.1 Hz)

6.80(1H, d, J=12.1 Hz)

9.59(1H,s)

EXAMPLES 6˜25

(a) 4-Methoxybenzyl7-phenylacetamido-3-chloromethyl-3-cephem-4-carboxylate (6 g),triphenylphosphine (3.4 g) and sodium iodide (1.94 g) were dissolved ina heterogeneous reaction medium consisting of a chlorinated hydrocarbonsolvent (36 ml) as listed in Table 1 below and water (36 ml). Theresultant reaction mixture was subjected to the reaction at atemperature of 32° C.±1° C. for 1.5 hours. After confirming thedisappearance of the starting material, the organic layer was separatedfrom the resulting reaction solution and then cooled to 3±1° C.Thereafter, a cold aqueous NaOH solution (containing 0.64 g of NaOHdissolved in 36 ml of water) was added to the cooled organic layer, withwhich the further reaction was then conducted at a temperature of 3±1°C. for 30 minutes.

(b) After confirming the disappearance of the starting material, theorganic layer containing 4-methoxybenzyl7-phenyl-acetamido-3-[(triphenylphosphoranylidene)methyl]-3-cephem-4-carboxylateso produced was separated from the resulting reaction solution and thendried over magnesium sulfate. The organic layer so dried was cooled tothe respective reaction temperature shown in Table 1.

After cooling, said organic layer was added with an alkanol solvent aslisted in Table 1 so that the alkanol as added and the chlorinatedhydrocarbon solvent were made to be present in the resultant mixture, inthe particular proportions (by volume) of them as shown in Table 1.Further, 4-methyl-thiazol-5-carbaldehyde (11.8 g) was added to theorganic phase. The resulting mixture was then subjected to the reactionat a reaction temperature as shown in Table 1 for 14 hours. After thecompletion of the reaction, the reaction solution so obtained wassubjected to HPLC. analysis in order to determine the proportion of theZ-isomer and E-isomer of 4-methoxybenzyl7-phenylacetamido-3-[2-(4-methylthiazol-5-yl)vinyl]-3-cephem-4-carboxylateas produced in said reaction solution. The conditions used for thedetermination by the HPLC. analysis were the same as those mentionedabove.

The reaction conditions used and the experiment results obtained inExamples 6˜25 are summarily shown in Table 1(a) below. In the table,BtOH shows butanol, PrOH shows propanol and MeOH shows methanol.

Comparative Examples 1˜2

By way of comparison, the reaction of thetriphenylphosphoranylidene-methyl cephem compound with4-methylthiazol-5-carbaldehyde as illustrated in Examples 6˜25 wascarried out at room temperature (25° C.±2° C.) for 14 hours in the samemanner as in Examples 6˜25. After the completion of the reaction, theratio of the Z-isomer to E-isomer present in the reaction solution asobtained here was measured by HPLC. analysis in a similar way.

The results of Comparative Examples 1˜2 are also shown in Table 1(b)below. These results of Table 1(b) clearly show that the proportions ofthe Z-isomer and E-isomer present in the product compound as obtainedare largely differentiated, depending upon the mixed solvent used andthe reaction temperature used. In particular, if the reaction iseffected at a temperature of −20° C.±2° C., the area ratio of theZ-isomer to E-isomer under the absorption peak of HPLC chromatogram ofthe reaction product, can reach such values that the area of theZ-isomer was 20 times or more and sometimes 30 times or more higher thanthe area of the E-isomer. Accordingly, the processes of this inventionevidently can achieve the selective production of the Z-isomer.

TABLE 1(a) Area ratio (Z:E) under the absorption peaks of Z-isomer to E-isomer in the Reaction chromatogram of HPLC Example Mixed solventtemperature of the reaction No. (Mix ratio, by volume) (° C.) solution 6CH₂Cl₂—BtOH (1:3) +3° C. ± 2° C. 14.8:1 7 CH₂Cl₂—BtOH (1:1) +3° C. ± 2°C. 16.9:1 8 CH₂Cl₂-isoPrOH (1:1) +3° C. ± 2° C. 17.5:1 9 CH₂Cl₂-n-PrOH(1:1) +3° C. ± 2° C. 17.9:1 10 CH₂Cl₂-n-PrOH (2:1) +3° C. ± 2° C. 19.9:111 CH₂Cl₂-n-PrOH (4:1) +3° C. ± 2° C. 18.7:1 12 CH₂Cl₂-t-BuOH (4:1) +3°C. ± 2° C. 16.9:1 13 CH₂Cl₂—BtOH (2:1) −20 ± 2 19.9:1 14 CH₂Cl₂-n-PrOH(3:2) −20 ± 2 19.2:1 15 ClCH₂CH₂Cl-n-PrOH (2:1) −20 ± 2 16.2:1 16CH₂Cl₂-n-PrOH (7:2) −20 ± 2 20.2:1 17 CH₂Cl₂-n-PrOH (3:1) −20 ± 2 21.6:118 CH₂Cl₂-n-PrOH (2:1) −20 ± 2 23.5:1 19 CH₂Cl₂-t-BuOH (2:1) −20 ± 225.8:1 20 CH₂Cl₂-n-PrOH (5:2) −20 ± 2 28.8:1 21 CHCl₃-n-PrOH (2:1) −20 ±2 25.0:1 22 CHCl₃-n-PrOH (5:2) −20 ± 2 31.0:1 23 CHCl₃-n-PrOH (3:1) −20± 2 29.8:1 24 CHCl₃-n-PrOH (7:2) −20 ± 2 26.8:1 25 CHCl₃-n-PrOH (4:1)−20 ± 2 27.0:1

TABLE 1(a) Area ratio (Z:E) under the absorption peaks of Z-isomer to E-isomer in the Reaction chromatogram of HPLC Example Mixed solventtemperature of the reaction No. (Mix ratio, by volume) (° C.) solution 6CH₂Cl₂—BtOH (1:3) +3° C. ± 2° C. 14.8:1 7 CH₂Cl₂—BtOH (1:1) +3° C. ± 2°C. 16.9:1 8 CH₂Cl₂-isoPrOH (1:1) +3° C. ± 2° C. 17.5:1 9 CH₂Cl₂-n-PrOH(1:1) +3° C. ± 2° C. 17.9:1 10 CH₂Cl₂-n-PrOH (2:1) +3° C. ± 2° C. 19.9:111 CH₂Cl₂-n-PrOH (4:1) +3° C. ± 2° C. 18.7:1 12 CH₂Cl₂-t-BuOH (4:1) +3°C. ± 2° C. 16.9:1 13 CH₂Cl₂—BtOH (2:1) −20 ± 2 19.9:1 14 CH₂Cl₂-n-PrOH(3:2) −20 ± 2 19.2:1 15 ClCH₂CH₂Cl-n-PrOH (2:1) −20 ± 2 16.2:1 16CH₂Cl₂-n-PrOH (7:2) −20 ± 2 20.2:1 17 CH₂Cl₂-n-PrOH (3:1) −20 ± 2 21.6:118 CH₂Cl₂-n-PrOH (2:1) −20 ± 2 23.5:1 19 CH₂Cl₂-t-BuOH (2:1) −20 ± 225.8:1 20 CH₂Cl₂-n-PrOH (5:2) −20 ± 2 28.8:1 21 CHCl₃-n-PrOH (2:1) −20 ±2 25.0:1 22 CHCl₃-n-PrOH (5:2) −20 ± 2 31.0:1 23 CHCl₃-n-PrOH (3:1) −20± 2 29.8:1 24 CHCl₃-n-PrOH (7:2) −20 ± 2 26.8:1 25 CHCl₃-n-PrOH (4:1)−20 ± 2 27.0:1

Industrial Applicability

As is clear from the foregoing, it is seen that, according to theprocesses of this invention, when a 3-(2-substituted vinyl)-cephemcompound is to be produced by utilizing the Wittig's reaction, theZ-isomer of said cephem compound can be produced in a considerablylarger proportion than that of the E-isomer, that is, preferentially andin a high yield. The processes of this invention can be practised in afacile way and efficiently. The target product compound obtained by theprocesses of this invention has only an extremely small content of theE-isomer, as compared with the content of the desired Z-isomer. Theprocesses according to this invention are useful for the production of a3-(Z)-(2-substituted vinyl)-cephalosporin antibiotic excellent asantibacterial agent, or for the production of intermediates for use inthe synthesis of said antibiotic.

What is claimed is:
 1. A process for the production of the Z-isomer of a7-N-unsubstituted or substituted-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or an esterthereof represented by the following formula (IV)

wherein R¹ denotes a hydrogen atom or a mono-valent amino-protectinggroup, or R¹ denotes a 2-(2-N-protected orunprotected-aminothiazol-4-yl)-2-alkoxyiminoacetyl group having thefollowing formula (II)

where R⁵ is a hydrogen atom or a mono-valent amino-protecting group andR⁶ is a hydrogen atom, or R⁵ and R⁶ as taken together mean one di-valentamino-protecting group and R⁷ is an alkyl group of 1 to 4 carbon atoms,and wherein R² denotes a hydrogen atom, or R¹ and R² as taken togethermean one di-valent amino-protecting group and R³ denotes a hydrogenatom, a pivaloyloxymethyl group or an ester-forming group as acarboxyl-protecting group, and R⁸ denotes a hydrogen atom, an alkylgroup of 1 to 4 carbon atoms, a trifluoromethyl group or a chloro group,wherein said process comprises reacting a 7-N-unsubstituted orsubstituted-amino-3-[(tri-substituted-phosphoranylidene)methyl]-3-cephem-4-carboxylicacid or an ester thereof represented by the following formula (I)

where R¹, R² and R³ each have the same meanings as defined above and R⁴denotes an alkyl group of 1 to 6 carbon atoms or an aryl group, or acompound represented by the following formula (I′)

where R¹, R², R³ and R⁴ each have the same meanings as defined above,with a 4-substituted or unsubstituted-thiazol-5-carbaldehyde representedby the following formula (III)

where R⁸ has the same meaning as defined above, in a mixed solventconsisting of one or more chlorinated hydrocarbon solvent(s) and one ormore lower alkanol(s) mixed at a mix ratio (by volume) in a range offrom 1:3 to 1:0.25, at a temperature of +5° C. to −50° C.
 2. The processaccording to claim 1, wherein the reaction of a compound of formula (I)with a compound of formula (III) is effected at a temperature of 0° C.to −50° C.
 3. The process according to claim 1, wherein the mix ratio ofthe chlorinated hydrocarbon solvent(s) to the lower alkanol(s) presentin the mixed solvent as used is in the range of 1:1 to 1:0.28, andwherein the reaction of a compound of formula (I) with a compound offormula (III) is effected at a temperature in the range of −10° C. to−30° C.
 4. The process according to claim 1, wherein the chlorinatedhydrocarbon solvent is a monochloro-, dichloro- or trichloro- (C₁ to C₂)alkane.
 5. The process according to claim 1, wherein the lower alkanolis an alkanol of 1 to 6 carbon atoms.
 6. The process according to claim1, wherein the reaction is effected in a mixed solvent consisting of amixture of chloroform or methylene chloride with n-propanol as mixed ata mix ratio (by volume) in the range of 1:0.25 to 1:0.4, at atemperature in the range of −18° C. to −23° C.
 7. A process for theproduction of a crystalline form of the Z-isomer of a 7-N-unsubstitutedor substituted-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl)vinyl]-3-cephem-4-carboxylic acid or an esterthereof having the following formula (IV)

wherein R¹ denotes a hydrogen atom or a mono-valert amino-protectinggroup, or R¹ denotes a 2-(2-N-protected orunprotected-aminothiazol-4-yl)-2-alkoxyiminoacetyl group of thefollowing formula (II)

where R⁵ is a hydrogen atom or a mono-valent amino-protecting group andR⁶ is a hydrogen atom, or R⁵ and R⁶ as taken together mean one di-valentamino-protecting group and R⁷ is an alkyl group of 1 to 4 carbon atoms,and wherein R² denotes a hydrogen atom, or R¹ and R² as taken togethermean one di-valent amino-protecting group and R³ denotes a hydrogenatom, a pivaloyloxymethyl group or an ester-forming group as acarboxyl-protecting group, and R⁸ denotes a hydrogen atom, an alkylgroup of 1 to 4 carbon atoms, a trifluoromethyl group or a chloro group,which process comprises reacting a 7-N-unsubstituted orsubstituted-amino-3-[(tri-substituted-phosphoranylidene)methyl]-3-cephem-4-carboxylicacid or an ester thereof having the following formula (I)

wherein R¹, R² and R³ each have the same meanings as defined above andR⁴ denotes an alkyl group of 1 to 6 carbon atoms or an aryl group, or acompound represented by the following formula (I′)

where R¹, R², R³ and R⁴ each have the same meanings as defined above,with a 4-substituted or unsubstituted-thiazol-5-carbaldehyde representedby the following formula (III)

where R⁸ has the same meaning as defined above, in a mixed solventconsisting of a mixture of methylene chloride, chloroform ordichloroethane with n-propanol at a mix ratio (by volume) in a range offrom 1:1 to 1:0.28 at a temperature in the range of −10° C. to −30° C.,thereby to obtain the reaction solution containing the Z-isomer of the7-N-unsubstituted or substituted-amino-3-[2-(4-substituted orunsubstituted-thiazol-5-yl) vinyl]-3-cephem-4-carboxylic acid or anester thereof of the formula (IV) above, then washing said reactionsolution with an aqueous potassium pyrosulfite solution, thereafterconcentrating the reaction solution, adding to the resultingconcentrated solution methanol or butyl acetate or a mixture thereof soas to crystallize the Z-isomer of the compound of formula (IV) out ofthe solution.
 8. The process according to claim 1, wherein the mix ratioof the chlorinated hydrocarbon solvent(s) to the lower alkanol(s)present in the mixed solvent as used is in the range of 1:0.5 to 1:0.4,and wherein the reaction of a compound of formula (I) with a compound offormula (III) is effected at a temperature in the range of −18° C. to−23° C.
 9. The process according to claim 4, wherein the chlorinatedhydrocarbon solvent is a methylene chloride, chloroform ordichloroethane, or a mixture of two or more of them.
 10. The processaccording to claim 5, wherein the lower alkanol is methanol, ethanol,n-propanol, isopropanol, n-butanol or t-butanol, or a mixture of two ormore of them.